The present invention relates to inhalation therapy units and especially to a valve for limiting the inspiration flow.
An aerosol atomizer is known from the EP-B-0 281 650, which consists of a substantially cylindrical basic body in which an atomizer nozzle is disposed for the generation of an aerosol and into which an air intake flue projects for the supply of ambient air. The outer opening of the air intake flue is closed by an inlet valve which is constructed as one-way valve. It permits the inflow of ambient air into the nebuliser housing when the patient inspires through a mouthpiece of the aerosol atomizer, but prevents the escape of the aerosol from the atomizer interior during the breathing intervals and for the event that the patent exhales into the aerosol atomizer. The known inhalation therapy unit is therefore constructed in such a manner that the patient can inspire an arbitrary volume of respiratory air, limited merely by the flow resistance defined by the shape of the atomizer.
However, the aim of an inhalation therapy is always the effective, low side-effect application of the medicine administered in aerosol form into the diseased lung regions. In this respect, an aerosol is generated in an inhalation therapy unit with a suitable droplet spectrum and in a suitable amount. This aerosol should be inhaled by the patient according to a defined breathing pattern, so that the aerosol droplets reach the desired deposition location in the lungs. Until now, it was necessary to train the patient with a view to this breathing pattern and an optimization of the breathing parameters, which in many cases led to considerable difficulties.
In these efforts, there are two contradictory requirements. On the one hand, namely, the inspiring of the aerosol should be as easy as possible for the patient, and on the other hand, a maximization of the effect of the inhalation therapy only occurs when an aerosol is inspired in such a manner that a deposition takes place at the desired location of the lungs. This procedure is influenced by the droplet size, the amount of aerosol, the amount of intake air, the inspiration flow and other parameters. With respect to the inspiration flow, until now it was only endeavoured to achieve a limitation in the inspiration path of the inhalation therapy unit by cross-section reductions (stenoses). Due to the increased flow resistance in the flow region to be realized, however, this frequently results in the encumbrance of the already weakened respiratory capacity of the patient.
An inspiration flow of up to a maximum of 30 l/min is aerosol-physically desirable in order to minimize the inertial separation, the so-called impaction, of the aerosol droplets in the upper respiratory paths and to increase the deposition probability in the lungs in the intended deposition location.
The expiratory process is of lesser significance. However, also during expiration the expiration flow should be within a certain range.
With this background, the object of the invention is to construct an inhalation therapy unit in such a manner that the maintenance of the aerosol-physically desirable ranges is simplified for the patient during respiration, without an additional encumbrance occurring for the patient upon respiration in these ranges.